[Raytrace] Optimization

[Peter John Smith]

: "Richard F.L.R. Snashall"  wrote


> using an appropriate field and the built-in Photopic wavelength
> selection:
>
>         wavelength  weight
>           0.470      0.091
>           0.510      0.503
>           0.555      1.000
>           0.610      0.503
>           0.650      0.107
>
> After optimization, the Polychromatic Strehl ratio was 0.840




> I found (and I have found this consistent using several different
> glass combinations) that, if I optimize instead for wavelengths
> 0.482, 0.522, 0.571, 0.628, and 0.670 (adding 12 ... 20 nm to
> the each) that the Strehl ratio improves to 0.860.


I suspect that the discrepence is totally due to your choice of what Zemax
calls the 'primary' wavelength.

This is the weavelength chosen for the reporting of any wave errors.

Most likely Zemax was automatically set for 550 in the first case, then 571
in the second case. The Strehl would increase with larger wavelengths so
this is consistent.

How this impacts on the calculation of the 'Polychromatic Strehl' I am not
sure but it would be easy to introduce a sixth wavelength of 550 in the
second case, giving it a weighting of 0 (or if it dont like that 0.00001)
and setting it as the Primary wavelength and then repeat the calculations
with this.  This should confirm what is happening.

I know I have had inconsistencies traced to the accidental changing of the
primary wavelength which went unnoticed for quite a while.

Peter Smith.